Elbow tendinitis lands reliever Guerrier on DL

LOS ANGELES -- Dodgers reliever Matt Guerrier, signed in part to be the bullpen workhorse, was placed on the 15-day disabled list Tuesday because of right elbow flexor tendinitis.

Guerrier had an MRI, which revealed no issues with the ligament that leads to Tommy John surgery. He received a platelet-rich plasma injection, will rest for several days, then begin tossing.

The Dodgers called up left-hander Michael Antonini from Triple-A Albuquerque to replace Guerrier in the bullpen.

Guerrier last pitched a week ago and the placement on the disabled list was retroactive to April 18. He said he's been dealing with the condition since Spring Training and it doesn't bother him when he's pitching, but he has trouble getting loose the next day.

"I could pitch through it, but it puts the guys in the bullpen in a tough position when I need a day off after every game I pitch," he said.

Manager Don Mattingly said the decision to put Guerrier on the DL was made after Monday night's game.

"We thought it was normal stuff the first couple days, but when it extended it was like, 'What's going on here?'" Mattingly said. "The biggest problem is he doesn't know how he feels the next day. I could tell last night by his answers that he didn't know what's going on."

Guerrier had a 2.70 ERA in seven games but walked five in 6 2/3 innings. Guerrier signed a three-year, $12 million contract before the 2011 season. This is the first time he's been on the disabled list with an arm injury. The only other time he's been disabled was in 2006 for a fractured thumb.

Rivera exits in sixth after straining hamstring

LOS ANGELES -- Dodgers first baseman Juan Rivera, who homered earlier in Tuesday night's 4-3 loss to the Braves, exited in the bottom of the sixth inning with a left hamstring strain.

He will have his left leg evaluated Wednesday to determine if he needs to go on the disabled list.

Rivera pulled up halfway to first base and jogged the rest of the way on a deflected infield single off Atlanta starter Mike Minor. After a brief discussion with manager Don Mattingly, Rivera left the game, but without a noticeable limp.

"We'll know a whole lot more [Wednesday]," Mattingly said. "Right now it sounds like it's the attachment really low, just above the knee. I don't know how to categorize it at this point. He could come in tomorrow bad or really good and it will be a couple days thing."

Rivera started at first base in place of James Loney, who replaced him.

Lefty Antonini recalled in first promotion to bigs

LOS ANGELES -- The Dodgers on Tuesday called up Michael Antonini from Triple-A Albuquerque to replace injured reliever Matt Guerrier in the bullpen.

Antonini was 1-0 with a 4.26 ERA over four games (three starts) for the Isotopes. This is the first Major League promotion for the 26-year-old Antonini, acquired by the Dodgers from the Mets on Dec. 27, 2010, for Chin-lung Hu.

A left-handed starter, Antonini's stay in Los Angeles could be short. Reliever Todd Coffey is eligible to come off the disabled list Sunday. Coffey is scheduled for Minor League rehab innings Wednesday and Friday. If those go without an issue, he's likely to be activated Sunday, with Antonini returning to Albuquerque.

Manager Don Mattingly said the club chose Antonini to counter Atlanta's left-handed hitters.

Antonini said he got the call around 1 a.m. Tuesday morning while the club was in Oklahoma City. He called his mother in Philadelphia and woke her up with the good news.

"I was a little surprised, but I was throwing the ball good there and once you get a rhythm, you never know what can happen," Antonini said.

Belisario set to head out on Minors assignment

LOS ANGELES -- Troubled Dodgers reliever Ronald Belisario will start a Minor League rehab assignment next week and is eligible to return from a 25-game suspension for violating Major League Baseball's drug policy on May 4.

Belisario, however, is out of options and the Dodgers must decide if he's ready to help the club on that date. If not, they cannot send him to the Minor Leagues unless he clears waivers, but he could be taken by another club.

Belisario has not pitched in the Major Leagues since 2010 and spent the entire 2011 season on the restricted list, reportedly with drug problems that prevented him from obtaining a work visa.

Manager Don Mattingly said Belisario has been working out at the club's Camelback Ranch-Glendale complex in Arizona.

Ken Gurnick is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.